The invention relates to a vertically adjustable hitch for an agricultural tractor, wherein the hitch includes a retainer which is guided vertically and which can be locked.
DE-OS-29 10 164 discloses a trailer coupling for agricultural tractors. The coupling consists of a coupling socket and a support plate rigidly connected thereto, which is guided between two perforated rails fastened to the tractor and can be positioned vertically and can be locked in various positions by means of a pin penetrating the perforated rails and the support plate. Due to the relatively large weight of the trailer coupling, the trailer coupling is supported by two compression springs with a particular spring characteristic.
DE-A1-38 16 359 discloses a trailer coupling for agricultural vehicles that can be infinitely variably adjusted in height by means of a power drive consisting of two piston and cylinder arrangements. To position the trailer coupling, the vehicle drive must be operating so that the piston and cylinder arrangement can be supplied with operating pressure.
The European patent application EP-A1-0 294 509 also discloses a trailer coupling that can be adjusted in height with a coupling support that can be positioned by means of a spindle and nut drive. This configuration is costly to manufacture and requires frequent servicing of the spindle and nut drive.